It is known in the art to thermally spray coat the cylinder walls of aluminum engine blocks with a ferrous-based material using high velocity oxygen-fuel (HVOF) systems. Examples of prior HVOF systems include those disclosed in U.S. Pat. Nos. 5,014,916; 5,148,986; 5,275,336; 4,578,114 and 5,334,235, wherein a jet of oxygen and gaseous fuel is ignited within an HVOF gun to melt a feed wire of ferrous-based material which is expelled from the gun by the jet of burning oxygen-fuel onto the surface of the cylinder wall. The rate of application is limited by the rate of melting of the wire feed material.
It is an object of the present invention to increase the efficiency of such HVOF systems.